You said "Have any of you used our first polymer power bank" not "Have any of you used our first 10K polymer power bank".
So the smaller the portable charger the less useful it is as a charger and the more it becomes an emergency item you keep for the unexpected or the atypical worse days. So the need is to be so small it has little reason to not be packed, and maximum functionality. To get enough charge to make a call type so 3K is a good capacity. Those emergency type situations benefit from having a torch as then the one casing to protect the battery can encase an LED output with the recharging and the charging.
So merge this with this
A typical use case is a ladies purse where the lady has this with the whole time and might only use it once a month, more so in winter, so if you're thinking Li Poly then making more credit-card flat shape helps it slide in a typical modern ladies purse.
Let's put it this way, if you made it I'd buy at least 3 for the next winter (so buy like 9 months from now).
If you want to do this an Anker way then have it high performance, 2A output and 2A input (or as much above 1A you can for the 3K type cell) and consider a built-in cable so I'd buy the MicroB version for someone with the older Android, Lightning for an iphone user and USB-C for newer Android.